Summer vacation is officially underway, which means it’s already time to start getting ready for next semester. I’m teaching the first half of the introduction to world history again in the fall, so I’ll be spending part of the next few months brushing up. Teaching a course for the third or fourth time is sort of like doing another draft of a piece of writing; you can go back over the material and tinker with the parts that need work.

These survey courses can be difficult, because you’re inevitably going to be stepping outside your immediate area of expertise. The difference between doing, say, nineteenth-century American history and ancient Mesopotamian history is quite profound—like the difference between ornithology and bacteriology. Since introductory history surveys cover the whole span of the human past, those of us who teach them have to exercise academic muscles that we wouldn’t normally use otherwise.

It can be challenging, but it’s also a neat opportunity. You essentially get permission to become a temporary archeologist, Egyptologist, or medievalist and hold forth on topics you’d never normally discuss. I’ll never be able to write a scholarly book on Alexander the Great or excavate a Roman villa, but I’ve got a license to dabble in this stuff anyway. It’s sort of like professional escapism, and it’s one of the great pleasures that teaching affords.